Dsp-Controlled Input Limiter; Dbu/E01 Block Diagram - Lectrosonics DBu/E01 Instruction Manual

Servo Bias Input and Wiring
The DBu/E01 input preamp is a unique design that deliv-
ers audible improvements over conventional transmitter
inputs, is easier to use and much harder to overload.
It is not necessary to introduce pads on some mics
to prevent overload of the input stage, divide the bias
voltage down for some low voltage mics, or reduce the
limiter range at minimum gain settings.
Two different microphone wiring schemes are available
to simplify and standardize the configuration. Simpli-
fied 2-wire and 3-wire configurations provide several
arrangements designed for use only with servo bias
inputs to take full advantage of the preamp circuitry.
Other wiring schemes are compatible with Servo Bias
and conventional inputs.
A line level input wiring provides an extended frequency
response with an LF roll-off at 35 Hz for use with instru-
ments and line level signal sources.

DBu/E01 Block Diagram

+5V
Servo Bias
Supply
Input
Jack
Input
Preamp
Gain
Adj
Shunt Limiter Control
Limiter
Oscillator
VCTXO
36.864 mHz
Rio Rancho, NM
DBu/E01 Transmitter
Bias Voltage
0, 2 or 4V
A-D
Converter
HI/Lo
Audio
Pass
Filter
I2S
Microprocessor
Key Received
Blue LED
PLL Ref
Phase Locked Loop

DSP-controlled Input Limiter

The transmitter employs a digitally-controlled analog
audio limiter prior to the analog-to-digital converter.
The limiter has a range greater than 30 dB for excellent
overload protection. A dual release envelope makes the
limiter acoustically transparent while maintaining low
distortion. It can be thought of as two limiters in series,
connected as a fast attack and release limiter followed
by a slow attack and release limiter. The limiter recovers
quickly from brief transients, so that its action is hidden
from the listener, but recovers slowly from sustained
high levels to keep audio distortion low and preserve
short term dynamic changes in the audio.
D-A Convert-
er I + Q
Baseband
Signals
I2S
(2) AA
Batteries
Firmware
Update
UART
Security Key
Keypad
Voltage Controlled
Oscillator
Control
Digital Belt-Pack Transmitter
Low
pass
filters
Switching
Power
Supply
Power
LED
Tricolor
IR Port
USB
Jack
IQ Modulator
Low
Buffer
Pass
Filter
Filters
Final
Amplifier
3